Due to the rapid escalating changes in the price of gold and the consequent cost to dental patients, a great need exists for a low gold content dental alloy which, however, still exhibits the properties needed for excellent clinical results. Many of the present low gold or no gold content dental alloys on the market do not exhibit properties which allow them to be closely adapted to tooth structure and therefore cannot be used for inlays, onlays, and 3/4 crowns. Furthermore, in the case of nickel-chromium base alloys, some have been implicated in allergic response reactions in patients. It was important to design an alloy utilizing metals which have been used in dentistry for a great period of time insuring a record of low incidence of toxicity and allergic responses.
It was also important to design an alloy which could be utilized with present equipment and the normal standard techniques so as to prevent added costs of new equipment and training.
To my knowledge, the following are the most pertinent U.S. Patents relating to the subject matter of this application:
U.S. Pat. No. 1,296,938 PA1 U.S. Pat. No. 2,198,400 PA1 U.S. Pat. No. 2,716,605 PA1 U.S. Pat. No. 3,929,475 PA1 U.S. Pat. No. 3,667,936 PA1 U.S. Pat. No. 3,767,391 PA1 U.S. Pat. No. 3,819,366 PA1 U.S. Pat. No. 4,007,040 PA1 U.S. Pat. No. 4,012,228 PA1 U.S. Pat. No. 4,179,288 PA1 U.S. Pat. No. 4,194,907
Together with the references made of record during the prosecution of such patents.
In my opinion, none of the foregoing U.S. Patents anticipate the invention herein disclosed and claimed, nor would it have been obvious to a man skilled in the art to evolve this invention from such prior art patents.